Design strategies reaction chemistry

In Part V we show you how to pull all the previous information together and use it to develop strategies for designing synthesis reactions. We talk about both one-step and multistep synthesis as well as retrosynthetic analysis. Then we tackle the dreaded organic roadmaps. (We all wish we had an organic chemistry GPS here.)... 

The first column of each month is devoted to a total synthesis. So many outstanding total syntheses appear each year, no attempt was made to be comprehensive. Rather, each synthesis chosen was selected because it contributed in some important way to the developing concepts of synthesis strategy and design. It is important to note that even if a total synthesis was not featured as such, all new reaction chemistry in that synthesis was included at the appropriate place in these Highlights. 

Small-molecule libraries may be created by a variety of methods. These include traditional solution chemistry performed in parallel using multiple reaction vessels so that the individualized chemistry performed in each vessel is, in effect, spatially encoded and hence the structure of the product is implicit by vessel. Alternatively, the chemistry can be performed on a solid support, usually polystyrene beads, in individual vessels, or the supports can be combined into pools where each bead is viewed as a separate reaction vessel. This allows a whole range of design strategies to be employed (vide supra). According to a recent literature survey, two-thirds of reported libraries are prepared on solid support and one-third by solution chemistry. ... 

If you are planning to become a chemist, you can use this understanding in a creative way to synthesize new molecules and to design new reactions. Indeed that s how many organic chemists view main-group chemistry, as a fount of new reagents and synthetic strategies. 

Transition metal-catalyzed domino reactions are of special interest in the preparation of natnral products and analogs as important lead structures in the development of bioactive componnds. Moreover, they can be used for the synthesis of any other types of compound as well as being used in combinatorial chemistry. Recently, a nnmber of excellent transition metal-catalyzed cascades were developed and reported which have attracted significant attention for synthetic chemists, dne to their high efficiency and diversity. Using well-designed strategies, transition metal-catalyzed cascades have been used successfully in the total synthesis of some natural products. 

The modem organic chemist has a variety both of reagents and reactions far beyond those we have looked at here. If you study organic chemistry to a more advanced level you should meet many of them but you will find that the principles of their design and use are the same as those you have learnt in this programme. We have now finished the basic types of disconnection and must look at the strategy of synthesis. 

While the majority of the chemistry strategies and synthesis design is equivalent to standard analogue producing approaches, a unique feature can be taken into account based on the relative photosensitivity of the probes. The introduction of the radio or other types of labels can also modify the reaction sequences. 

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